Door-locking apparatus for a cooking oven

ABSTRACT

A cooking oven having an access door and a safety-locking apparatus for a latching mechanism of said door, said safetylocking mechanism including a solenoid operated locking member requiring an independent manual operation to unlock the latching mechanism in order to move the latch from the unlatched to the latched position and vice versa. A high-current switch is included operable by an actuating member responsive to operation of the door latching mechanism such that an appliance, such as a pyrolytic type of self-cleaning oven, may not be operable in the heat cleaning process unless and until the door latching mechanism, and thereby the door, are in the latched and lockedclosed position. A cam surface on the switch actuating member serves to operate the high-current switch and also provides mechanical advantage for the forced breaking of the switch contacts should they become welded together.

United States Patent 11 1 TlMER.

SWITCH l CLEAN, rs

Staples 1 July 8, 1975 [54] DOOR-LOCKING APPARATUS FOR A R26,944 8/1970 Getman 219/413 COOKING OVEN [75] Inventor: Paul R'. Staples, Louisville, Ky. Prlmary Exammer volodymyr Mayewsky [73] Assignee: General Electric Company, [57] ABSTRACT Lou1sv1l1e, Ky. A cooking oven having an access door and a safety- Flled: May 1974 locking apparatus for a latching mechanism of said [21] APPL 470,724 door, said safety-locking mechanism including a solenoid operated locking member requiring an independent manual operation to unlock the latching mecha- CL 219/394; 126/197; 219/396; nism in order to move the latch from the unlatched to 219/393; 219/413; 292/D1G 69 the latched position and vice versa. A high-current [51] Int. Cl. F27d 1/02 Switch i included operable by an actuating member [58] Fleld of Search 21'9/393, 412, responsive to operation of the door latching mecha- 219/413; 126/197; 292/113 1316- 69; nism such that an appliance, such as a pyrolytic type 337/319 of self-cleanin oven, may not be operable in the heat g cleaning process unless and until the door latching [56] References cued mechanism, and thereby the door, are in the latched UNITED STATES PATENTS and locked-closed position. A cam surface on the 3,041,440 6/1962 D1115 219/394 Switch actuating member serves to Operate the high- 3,293, 0 12/1966 Welsh 219/393 current switch and also provides mechanical advan- 3,301,999 1/1967 Chisholm... 219/393 tage for the forced breaking of the switch contacts 3,317,708 5/1967 Bowling 219/412 hould they become welded together, 3,750,643 8/1973 Fowler et al 126/197 3,821,681 6/1974 Staples et a1 337/319 7 Claims, 5 Drawlng Figures R26,943 8/1970 Barber 219/413 131%? 13a ff: f l IT o 1= 11111 I N CLEAN l 1 BAKE 1 O--- 100 E Ll Emma? H7 o-4 Ha I I BK, B P I MULLKBN BRQIL L2 CLEAN 104 m 106 l 1 Z! :jgmruae J OFF, CLEAN 2 1 ROLLER 1 i ROT' TWEN I fit/ l i MOTOR I a. I PILOT I LAMP I OVEN CLEAN LAMP N I 166 I l I 100, I

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LOGIC. svurrc 1 DOOR-LOCKING APPARATUS FOR A COOKING OVEN BACKGROUND OF THE INVENTION 1. Field of the Invention:

The present invention relates to locking apparatus for an appliance door latching mechanism and more particularly, to safety locking apparatus requiring an independent operation for locking an appliance door latching mechanism and for preventing predetermined phases of operation of the appliance until the access door is in the latched and locked closed position.

2. Description of the Prior Art:

Safety dictates that certain appliances be provided with means for preventing at least certain phases of the operation of the appliance unless and until the access door associated therewith is in its closed and locked position, this requiring a definite step independent of the closing of the access door. A pyrolytic type of selfclean oven, such as that disclosed in US. Pat. No. 3,l2l,l58Hurko and assigned to the same assignee as the present invention, is one such appliance requiring such a safety-locking mechanism Such an oven would, in the self-cleaning process, reach temperatures about 900 F and it is certainly desirable, if not absolutely necessary, that this self-clean process not be started inadvertently and further that the access door to the oven not be openable once the temperature within the oven reaches a predetermined level.

An oven door latching system useful in accomplishing this result is disclosed in US. Pat. No. RE 26,944-Getman, assigned to the same assignee as the present invention. Therein is disclosed apparatus for insuring that the oven door be both closed and locked before the self-cleaning process can be initiated as well as for insuring that the oven door cannot be unlocked as long as the oven temperature is above a predetermined level. Disclosed therein is a locking means for the door locking mechanism, a portion of which is included in a low voltage circuit working in conjunction with a low voltage relay type of thermostatic control device. However, in that arrangement, a cumulation of tolerances problem arises with regard to the operation of the latch-logic switch actuated by the door latch mechanism. Furthermore, this hot-wire relay type of thermostatic controller is slow to respond and thereby produces a difficult and expensive calibration process during the manufacturing operation. An evolution process results in the replacement of the hot-wire relay controller device by a solid-state temperature controller and ultimately, by a hydraulic, thermostatic controller (such as the dual range hydraulic thermostatic control device disclosed in allowed application, Ser. No. 368,275 Staples et al, filed June 8, 1973, now US. Pat. No. 3,821,681, and assigned to the same assignee as the present invention) wherein the full line current for the heating elements of the oven passes through and is switched by the thermostatic control device. This then obviates the need for the low voltage circuit as disclosed in the Getman patent but at the same time brings about a need for a safety-locking device making use of a high-current switch therein which can handle the current load for the heating elements.

Another problem arises, however, that of contact welding in the high-current, latch-logic switch of the door-latch, locking mechanism, this resulting from the slow make and break of the switch contacts. Of course,

the immediate thought is to use a snap-acting type of switch. However, if a switch of this type were to have its contacts become welded, there would be no mechanical coupling of sufficient force to break the weld.

A reliable safety locking apparatus is needed therefore for use in locking an appliance access door latching means and which is capable of switching line voltage and the corresponding currents needed for operating such elements as the electric resistance heaters in a domestic self-cleaning oven.

By the present invention, there is provided an improved safety locking apparatus for an appliance door latching means, which apparatus is rather simple of construction, highly reliable, and of relatively low cost and which is useful for preventing predetermined phases of operation of the appliance until the access door thereof is in the latched and locked-closed position and which solves the problem of contact welding of the latch-logic switch therein.

SUMMARY OF THE INVENTION In accordance with the present invention, there is provided in an appliance having an access door and means for latching the door in the closed position, safety locking apparatus requiring an intentional and independent operation for locking the latching means in the latched and unlatched modes, respectively. A support member is secured within the appliance and has the latching means secured thereto. A high-current electrical switch, having a set of contacts, is mechanically associated with the support member and serves as a latch-logic device for preventing predetermined phases of operation of the appliance until the access door is in'the latched and locked-closed position. Movable means are provided associated with the support member and responsive to operation of the latching means for actuating the switch, the movable means being provided with at least one camramp surface for mechanically engaging the switch to effect operation thereof and for providing mechanical advantage to break possibly welded contacts in the switch. A locking member is provided associated with the support member for preventing operation of the switch actuating means until intentionally and independently operated, both when the door is latched and when unlatched, and for preventing predetermined phases of operation of the appliance until the locking member is in the locked position.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings:

FIG. 1 is a side elevational view, broken away, of a domestic range including an oven of the pyrolytic, selfcleaning type, broken away to show the relationship thereto of the preferred embodiment of the present invention;

FIG. 2 is an enlarged view taken generally along the lines 2-2 of FIG. 1;

FIG. 3 is an exploded, perspective view of the preferred embodiment of the present invention, arranged to better show individual components thereof in relation to each other;

FIG. 4 is a cross-sectional view taken generally along the lines 4-4 of FIG. 2 and enlarged to more clearly show the operating relationship of certain components; and

FIG. 5 is a schematic representation of a power and control circuit useful in a pyrolytic, self-cleaning type of electric oven embodying the safety-locking apparatus of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, there is shown an appliance such as free-standing electric range which includes a caabinet 12 having an access door 14 for gaining access to an oven 16 (only a portion of which is shown by phantom lines) located therein. Access door 14 is of the drop-down type and is arranged to seal the oven 16 by appropriate means (not shown). A control panel 18 is provided, only a portion of which is shown, upon which are located the various controls and switches needed for the proper operation of such a range.

Oven 16 is of the pyrolytic, selfclean type such as that described in the aforementioned Hurko U.S. Pat. No. 3,121,158. With such an arrangement, it has been found necessary to provide means such as door latch mechanism 20 for latching the door 14 in the closed position. Door latch mechanism 20 may be of the type disclosed in U.S. Pat. No. 3,367,697Fox, assigned to the same assignee as the present invention. There is also provided safety-locking apparatus for locking the door latch 20 both in the latched and unlatched modes.

As shown in FlG. 2, door latch 20 includes a manually-operable handle lever 32 extending through an elon gated slot (not shown) on the front edge of the upper portion of cabinet 12 in a position just above and parallel to the top edge of the oven door 14. Handle lever 32 is pivotally secured within a bracket member 34 about an axis pin 36. Handle lever 32 is shown in the unlatched position and rotation thereof through an angle of about 60 in a horizontal plane serves to actu ate a latching bolt 38 which is pivotally actuated by several pin and slot connections between a recessed position as shown in FIG. 2 to a latching position wherein the bolt 38 is generally perpendicular to the front wall of the oven and in mating engagement with a slot 39 partially within the oven door 14. Further description of the operation of door latch 20 is not necessary to this disclosure but may be had by reference to the aforementioned Fox patent.

In accordance with the present invention, and referring generally to FIGS, 2 and 3, safety-locking apparatus 30 is provided requiring an intentional and independent operation for locking the door latch 20 in both the latched and unlatched modes. Safety-locking apparatus 30 includes a support member such as an elongated, generally U-shaped channel 40 suitably secured to the latch bracket 34 which is suitably secured to the cabi net 12. Also forming a part of the support member is a cover 42 arranged to be suitably secured to U- channel 40. A high-current electrical switch 44 is me-. chanically secured to the cover 42 and is responsive to a switching actuating means such as movable bar 46 for actuation. Movable bar 46 is nested within U-channel 40 and is pivotally connected to door latch 20 as at pin 48. Bar 46 then is free to travel in a longitudinal direction in response to operation of handle lever 32 of door latch 20. In actual operation, bar 46 is free to travel approximately 1 inch as handle-lever 32 is rotated from the unlatched position through the approximately 60 to the latched position. The operation of switch 44 by switch actuating bar 46 will be discussed more thoroughly hereinafter.

Also forming a part of safety-locking apparatus 30 is a locking member such as locking bar 50 provided with a pivoting surface 51 and a pair of tabs 52 for location and engagement in a pair of slots 54 located on stationary U-channe'l'40. Locking bar 50 then is vertically pivotable about the U-channel 40 and is further provided with a second pair of tabs 56 arranged for engagement with two sets of notches located on the movable bar 46. Notch set 58 corresponds to the unlatched position of the door latch and notch set 60 corresponds to the latched position thereof. By this arrangement then, movable bar 46 and thereby handle-lever 32 are not free to move if locking bar 50 is in its locked position, that is, if the locking bar is downward in locking engagement with movable bar 46. In other words, if door latch 20 is in its unlatched position, an intentional and independent operation must be performed to lift locking bar 50 from its locked position in locking engagement with movable bar 46 in order to place the door latch mechanism into the latched mode or position. To facilitate the operation of locking bar 50, there is provided an electroresponsive device such as solenoid 62 having an armature 64 coupled mechanically with locking bar 'SO, such that energization of solenoid 62 causes armature 64 to be drawn upwardly thereby effecting the lifting of tabs 56 of locking bar 50 from engagement with the respective notches of movable bar 46 thereby allowing the operation of the door latch mechanism. Upon the de-energization of solenoid 62, armature 64 falls back downward, partially in response to a compression spring 66 which serves to force locking bar 50 back into locking'engagement with movable bar 46. Locking bar 50 in the up or unlocked position, engages switch 44, a normally closed device as will be hereinafter described to open the switch contacts to prevent actuation of certain portions of a circuit, to be described later. If for any reason, the locking bar 50 is in the unlocked position, the switch 44 will be in the contacts-open state. An independent manual control may be provided on the control panel 18 for closing a control circuit for effecting momentary energization of solenoid 62-.

Returning now to operation of the high-current switch 44, it can be seen in FIG. 3 that movable bar 46 is provided with a cam-ramp surface 68 for mechanically engaging switch 44 to effect operation thereof. Referring also to FIG. 4, switch 44, which for purposes of this embodiment of the invention has been chosen to be of the normally closed type, and functions with a slow make and break of the contacts, is shown in the contacts-open position. Switch 44 is provided with a plunger 70 for engagement with cam-ramp surface 68 for effecting operation of the switch. As shown in this view, door latch mechanism 20 is in the unlatched position where it is desired that switch 44 be in the open state. Plunger 70 normally travels through a distance vertically of about one quarter inch and here is shown in its uppermost position. As can be envisioned then, when door latch 20 is in its latched and locked position, cam ramp surface 68 will have moved to the left (as viewed in FIG. 4) by approximately 1 inch thereby allowing plunger 70 to clear cam ramp surface 68 thereby resting in its full down position which corresponds to the switch normally closed state. Since switch 44 is of the high-current type and for such an application in a pyrolytic type of self-clean oven, it carries the line voltage and full current for theelectrical resistance heating elements of the oven, theswitch contacts are prone to welding. This problem has been obviated by the mechanical advantage of the cam ramp surface 68 making forced mechanical contact with plunger 70 thereby causing the breaking of the contacts of switch 44 should they become welded.

Turning now to FIG. 5, there is shown, by schematic representation, a circuit useful for the operation of a pyrolytic type of self-cleaning oven and wherein the present invention is incorporated. FIG. 5 then will give a better understanding of how switch 44 serves as a latch-logic device for preventing predetermined phases of operation such as the pyrolytic self-clean process until the access door 14 is in the closedand latchedlocked position. The oven is furnished with an electrical service of three wire Edison source of power; nominally 240 volts, single phase, 60 Hz AC, usually available in the average residence having adequate wiring. This voltage source is fed to the oven through a three wire cable having a pair of line wires L1 and L2 with a voltage of 240 volts therebetween and grounded neutral conductor N for supplying the electrical load of the oven. This electrical load is characterized by three heating elements; the baking element 100, a broiling element 102 and a mullion heater 104. The bake element 100 is usually located adjacent the bottom wall of the oven, the broil element 102 is usually located adjacent the top wall of the oven and the mullion heater 104 is usually located wrapped around the outside of the oven liner adjacent the front opening for replenishing the heat loss through and around the door opening during a high temperature, pyrolytic, heat cleaning operation. These heating elements 100, 102 and 104 are arranged in circuits in combination with an oven select switch 106 for setting up varied combinations of heating elements at different voltages to obtain a variety of heating rates. A manually settable oven temperature controller 108 including a logic switch is also provided for controlling the temperature within the oven at preselected temperatures during baking operations and a maximum temperature during oven cleaning operations. Such a temperature controller 108 is arranged serially with the heating elements 100, 102 and 104 for opening and closing the power circuit to the heating elements as a function of oven temperature with relation to the temperature predetermined or preset by the temperature controller 108.

The oven select switch 106 is provided with a series of line input terminals denoted as L1, N, L, and L2, as well as a series of load terminals denoted as K, J, and P. Switch 106 is provided with a plurality of switch contacts 112 through 126. These switch contacts are labeled with the particular cooking or cleaning operation that is involved when such contacts are closed. For example, during a baking or a time baking operation, the contacts 112 and 113, 118 and 119, and 124 and 125 are closed. During a broiling operation, contacts 116 and 117, and l24 and 125 are closed. During a cleaning cycle, contacts 113 and 114, 115 and 116, 119 and 120, 121 and 122, and 125 and 126 are closed.

Should there be a component failure during an operation of baking, time baking or broiling and should the oven temperature rise above the preset temperature of the oven temperature controller 108 and reach a temperature of say 600 650 F, the first switch 130 of double-point thermal switch 132 would be caused to below about 540 F, the switch contacts 136 and 136'- are in their normally closed state to allow actuation of door interlock solenoid 62. Attemperatures above approximately 540 F, contacts l38and 138 are closed to provide power for cooling fan 140 which causes air to be circulated between the oven inner wall and the oven outer wall so as to keep the outer walls cooled. After a temperature dwell of approximately 10 F, or somewhere near approximately 55 0 F, normally closed contacts 136 and 136' are opened cutting power from the circuit feeding solenoid 62 and a momentary switch 142 thus preventing the electrical circuit for the door latch locking apparatus from being actuated. Contacts 138 and 138' remain closed until the interior temperature of the oven drops below approximately 540 F.

In order to set up the self-cleaning process andthe electrical circuit therefor, there are several preliminary operations that must first be performed. It is imperative that the oven access door 14 first be closed and then latched and locked before the self cleaning process can be initiated, and also that the door remain closed and incapable of being operated or opened while the oven temperatures are above normal cooking temperatures. In other words, the safety-locking apparatus of, the present invention must be actuated before the handle lever .32 may be shifted. This is accomplished by coupling solenoid 62 across line L1 and neutral conductor N through momentary switch 142. Thus at temperatures below the operating temperature of second switch 134, that is below approximately 540 F, it is possible to shift handle lever 32 by manually closing momentary switch 142 thereby energizing solenoid 62 which in turn picks up locking bar 50 allowing the operation of door latch mechanism 20. However at temperatures above normal cooking temperatures, that is above approximately 550 F, contacts 136 and 136 of second switch 134 will be opened thereby disabling energizing circuit for solenoid 62 thus preventing access to the oven during the heat cleaning cycle. Of course oven selector switch 106 and temperature controller 108 must be arranged by the operator to call for the self-cleaning process thereby closing the necessary contacts as hereinbefore described.

To facilitate an understanding of the operation of latch-logic switch 44, it is felt that it would be useful at this time to trace the circuit of operation for the selfclean process. Since such a self-cleaning process would normally be a timed operation, a switch 144 responsive to operation of a timer mechanism (not shown) is closed thereby coupling line L2 into a portion of oven selector switch 106. Since contacts and 126 are closed, you may further trace the circuit to switch 44, the latch-logic device. As has been described, switch 44 will be in the closed state when the access door 14 is in the closed and latched-locked position. Contacts 162 and 164 of the logic switch of temperature controller 108 are closed to apply power to neon lamp 166 to indicate that the self-clean process is under way. Then trace the circuit through to the temperature controller 108 and thence to the parallel combination of bake heating element 100, broiling element 102 and mullion heater 104. These are then coupled into oven select switch 106 through load terminals K and J, thence through the appropriate contacts to terminal N and the circuit is thence completed by continuing to neutral conductor N. The three heating elements 100, 102 and 104 are therefore connected in parallel at half-voltage across line L2 and neutral conductor N in order to obtain a heating rate somewhat lower than the heating rate of the normal baking operation. Since contacts 162 and 164 are closed, it is readily seen that heating elements 100, 102 and 104 cannot be energized unless switch 44 is closed and this only occurs when the access door is in the closed and latched-locked position and further when locking bar 50 is down in the locked position.

It is not felt necessary at this point to go into any further detail of the power and control circuit since the present invention is centered around a safety-locking apparatus useful in an oven during a pyrolytic selfcleaning process. It should be mentioned however that certain ranges are provided including a second oven of the pyrolytic self-clean type. With such an arrangement, it is desirable that only one of these ovens be operated in the pyrolytic self-cleaning process at any one time due mainly to the amount of heat generated in the process. Referring generally then to FIGS. 2, 3 and 4, it can be seen that for such an operation there may be provided a second high-current electrical switch 148 also responsive to operation of movable bar 46 for its operation. There has also been provided located on movable bar 46 a second camramp surface 150 for engaging this second high-current switch 148. With such an arrangement then, when the door latch and thereby access door 14 is in its closed and latchedlocked position, first switch 44 will be in its closed state while second switch 148 will be in the open state. Likewise when the door latch 20 and thereby the door 14 is in the unlatched mode, and the safety-locking apparatus is in the locked position, first switch 44 will be in the open state and second switch 148 will be in the closed state. This then provides an interlock such that both ovens cannot be placed simultaneously into the pyrolytic self-clean process.

It should be apparent to those skilled in the art that the embodiment described heretofore is considered to be the presently preferred form of this invention. In accordance with the Patent Statutes, changes may be made in the disclosed apparatus and the manner in which it is used without actually departing from the true spirit and scope of this invention.

What is claimed is:

1. A cooking appliance comprising an oven cooking cavity formed by a box-like oven liner and an access door, heating means for supplying heat energy into the oven cooking cavity, means for latching the door in the closed position, safety locking apparatus requiring an intentional and independent operation for locking the door latching means in the latched and unlatched modes, respectively, said safety locking apparatus comprising a support member secured within the appliance and having the latching means secured thereto;

a high-current electrical switch having a set of contacts, the switch being mounted on the support member and serving as a latch-logic device for preventing predetermined phases of operation of the appliance until the access door is in the latched and locked-closed position;

switch-actuating means associated with the support member and movable in response to operation of the door latching means forv actuating the switch;

said switch-actuating means including at least one cam-ramp surface for mechanically engaging the switch to effect operation thereof and for providing mechanical advantage to break possibly welded contacts in the switch; and

a locking member associatedv with the support member for preventing operation of the switchactuating means until intentionally and independently operated both when the door is latched and when unlatched and for preventing predetermined phases of operation of the appliance until the locking member is in the locked position.

2. A cooking appliance as recited in claim 1 further including an electroresponsive device responsive to operation of an independent manual control to become energized for unlocking the locking member.

3. A cooking appliance as recited in claim 2 wherein the support member is an elongated, generally U- shaped channel and the switch-actuating means is a movable bar nested within the channel and arranged such that operation of the door latching means serves to effect longitudinal motion thereof.

4. A cooking appliance as recited in claim 3 wherein the switch is of the normally-closed type and is in the contacts-closed state when the latching means and thereby the door is latched and locked closed, and upon unlocking and unlatching the door, the cam-ramp surface engages the switch to plate it in the contactsopen state thereby preventing predetermined phases of operation of the appliance.

5. A cooking appliance as recited in claim 4 wherein the locking member is a locking bar vertically pivotable about the channel and having a movable portion engageable in a locked position in either of two sets of notches in the movable bar, the two sets of notches corresponding to the latched and the unlatched positions, respectively, of the safety latching apparatus.

6. A cooking appliance, as recited in claim 1 wherein said oven cooking cavity is of the pyrolytic, selfcleaning type and the phase of operation to be prevented until the access door is latched and lockedclosed is the pyrolytic, self-cleaning oven process.

7. A cooking appliance as recited in claim 6 wherein the oven cooking cavity includes a second oven cooking cavity of the pyrolytic, self-cleaning type, the appliance further including a second, high-current electrical switch associated with the support member and a second cam-ramp surface associated with the switch- 

1. A cooking appliance comprising an oven cooking cavity formed by a box-like oven liner and an access door, heating means for supplying heat energy into the oven cooking cavity, means for latching the door in the closed position, safety locking apparatus requiring an intentional and independent operation for locking the door latching means in the latched and unlatched modes, respectively, said safety locking apparatus comprising a support member secured within the appliance and having the latching means secured thereto; a high-current electrical switch having a set of contacts, the switch being mounted on the support member and serving as a latch-logic device for preventing predetermined phases of operation of the appliance until the access door is in the latched and locked-closed position; switch-actuating means associated with the support member and movable in response to operation of the door latching means for actuating the switch; said switch-actuating means including at least one cam-ramp surface for mechanically engaging the switch to effect operation thereof and for providing mechanical advantage to break possibly welded contacts in the switch; and a locking member associated with the support member for preventing operation of the switch-actuating means until intentionally and independently operated both when the door is latched and when unlatched and for preventing predetermined phases of operation of the appliance until the locking member is in the locked position.
 2. A cooking appliance as recited in claim 1 further including an electroresponsive device responsive to operation of an independent manual control to become energized for unlocking the locking member.
 3. A cooking appliance as recited in claim 2 wherein the support member is an elongated, generally U-shaped channel and the switch-actuating means is a movable bar nested within the channel and arranged such that operation of the door latching means serves to effect longitudinal motion thereof.
 4. A cooking appliance as recited in claim 3 wherein the switch is of the normally-closed type and is in the contacts-closed state when the latching means and thereby the door is latched and locked closed, and upon unlocking and unlatching the door, the cam-ramp surface engages the switch to plate it in the contacts-open state thereby preventing predetermined phases of operation of the appliance.
 5. A cooking appliance as recited in claim 4 wherein the locking member is a locking bar vertically pivotable about the channel and having a movable portion engageable in a locked position in either of two sets of notches in the movable bar, the two sets of notches corresponding to the latChed and the unlatched positions, respectively, of the safety latching apparatus.
 6. A cooking appliance as recited in claim 1 wherein said oven cooking cavity is of the pyrolytic, self-cleaning type and the phase of operation to be prevented until the access door is latched and locked-closed is the pyrolytic, self-cleaning oven process.
 7. A cooking appliance as recited in claim 6 wherein the oven cooking cavity includes a second oven cooking cavity of the pyrolytic, self-cleaning type, the appliance further including a second, high-current electrical switch associated with the support member and a second cam-ramp surface associated with the switch-actuating means for mechanically engaging the second switch and arranged such that when the latching means is in the latched-locked mode, the first switch will be in the contacts-closed state while the second switch will be in the contacts-open state, and when the latching means is in the unlatched-locked mode, the first switch will be in the contacts-open state and the second switch will be in the contacts-closed state, thereby providing an interlock such that both ovens may not be placed simultaneously into the pyrolytic self-cleaning oven process. 